Electric discharge device



July 9, 1935. E. LUBCKE ELECTRIC DISCHARGE DEVICE Filed Jan. 11, 1934lNVENTOR 70.57 A Jbc/(e ATTORN Y WITNESSES Patented July 9, 1935 PATENTOFFICE 2,007,542 I Y ELECTRIC DISCHARGE DEVICE ErnstLiibcke,.Berlin-Charlottenburg, Germany,

assignor to Westinghouse Electric &-Manufacturing Company, EastPittsburgh, Pa., a cor:

poration of Pennsylvania Application January 11, 1934, Serial No. InGermany January 12, 1933 i 3 Claims.

My invention relates to an electrical discharge device and circuittherefor, and especially to a type of such device in which a dischargebetween two electrodes provides a source of electrons for 5 an anode.

In these types of discharge devices, the anode and grid are alwaysconnected with one of the discharge electrodes with the result that afluctuating voltage is impressed upon the grid circuit due to the ionbombardment. This fluctuating voltage may, under certain conditions,make itself very noticeable in a disturbing manner as by the productionof hum in the output circuit of broadcasting tubes.

It is an object of my invention to avoid theproduction of this variablevoltage.

More especially, an object of my invention is to connect the anode andgrid of the work or output circuit to an auxiliary or probing electrodeinstead of to either of the discharge electrodes.

Further objects of my invention will become apparent from an examinationof the accompanying drawing in which,

Figure l is a diagrammatic illustration of a tube and circuit thereforembodying my invention,

Fig. 2 is a graph illustrating the values'of current produced in theanode and grid circuits, and

Fig. 3 is a modification of Fig. 1.

Figure 1 of the drawing discloses an electrical discharge devicepreferably in the form of a mercury vapor tube having the cathode 7c andthe anode a providing a discharge path or are path therebetween. Theseelectrodes may have any suitable shape and be of any desired material.If desired, other gases, such as the noble gases, may take the place ofmercury vapor in the tube.

Adjacent to this discharge path between the cathode is and anode a arethe anode v and the grid g. Electrons from the discharge stream flowthrough the grid g to the amplifier anode c. That part of the controlspace of the tube in which the amplifier anode v is located is shut offin any desired manner relative to the arc space except for the passageof electrons, in order to prevent breakdowns. If the tube is of highcapacity, the anode o and grid g may be provided with cooling means suchas a stream of water flowing near, on or through these electrodes.

An auxiliary electrode 3, which may be desighated as a probingelectrode, is located in the discharge space between the cathode 7c andthe anode a. In Fig. l probing electrode s is disclosed adjacentthe'cathode. It may, however, have other positions such as the centralportion of the tube or a position adjacent the anode. This probingelectrode s may be of any desired shape and material and if the tube isof high capacity, this probing electrode 8 may take the form of a hollowcoil with a cooling stream of water passing therethrough. The work oroutput circuit includes the load or which is connected to the anode andalso to the probing electrode 3 and to the grid 9. This anode circuitincludes means for providing a suitable working potential such as thetransformer circuit 1'. A local battery I? may also be included therein.

Fig. 2 shows schematically the characteristic curves of discharge tubesembodying the invention. The anode current is designated by Iv and thegrid current by Ig. As is well known, the control of the tube isefiective with negative values of the grid current Ig.

The invention makes possible the variation of the value P of the voltageat which the grid current Ig becomes positive by selecting the locationof the probing electrode .5. The adaptability of 1 the tube is therebyincreased and the necessary pre-energization of the grid is decreased.

In sending tubes especially, the invention has the advantage of avoidingthe ion bombardment effect in tubes of the prior art. These prior arttubes had their anode and grid circuits connected directly to thecathode k with the result that the grid had applied thereto, in additionto the control voltage, a variable or fluctuating voltage caused by ionbombardment. This voltage under certain conditions produces a verynoticeable burn or noise. In the invention, however,

the anode circuit and grid circuit are connected to the probingelectrode and the voltage caused by the discharge and superimposed onthe grid voltage is so much less as to be negligible in its efiect.Furthermore, the frequency of the two voltages is difierent which alsoaids in making it negligible in applicants invention.

Fig. 3 discloses a modification in which the disturbing grid voltage maybe kept separate from the control grid by providing a second grid suchas' the grid h. The circuit of the grid h includes the probing electrodes and the load or work circuit w and an anode v as in Fig. 1. The grid gis, however, connected with the cathode is of the auxiliary discharge inFig. 3. The current In occurring at the grid h is an electron currentwhile that occurring on the grid 9 is an ion current.

The use of a cooling means makes it possible to locate the electrodes ofthe tube, particularly the probing electrode at such points where thevoltage of the discharge path shows no gradients.

Although I have described herein certain specific embodiments of myinvention, other modifications will be apparent to those skilled in theart. My invention, therefore, is not to be limited, except insofar as isnecessitated by the prior art and as indicated in the appended claims.

I claim as my invention:

1. An electrical discharge circuit comprising a discharge device havinga pair of electrodes therein providing a discharge path therebetween, anauxiliary electrode extending across said discharge path, an anodeadapted to receive electrons from said discharge path, and a workcircuit, said work circuit connected to said auxiliary electrode andsaid anode.

2. An electrical discharge circuit comprising a discharge device havinga pair of electrodes therein providing a discharge path therebetween, an

in providing a discharge path therebetween, an 10 auxiliary electrode insaid discharge path, an anode adapted to receive electrons from saiddischarge path, two grid members adjacent said anode, one of said gridmembers connected to one of said discharge electrodes, and a workcircuit, said work circuit connected to said auxiliary electrode, saidanode and the other of said grid members.

ERNST LiiBcKE.

